605 Geological Society. 



February 25th, 1914.— Dr. A. Smith Woodward, F.E.S., President, 

 in the Chair. 



The following communication was read: — 



' Correlation of Dinantian and Avonian.' 

 By Arthur Vaughan, M.A., D.Sc, F.G.S. 



The present paper records the results of applying the time-scale 

 deduced from the South-Western Province to the Belgian sequence, 

 and shows that the faunal succession is practically the same in both 

 provinces. Even the specialized and locally exaggerated facies 

 which fonn so striking a feature of the Belgian Province (such as 

 the 'petit granit,' the ' Waulsortian,' and the ^ sublcBvis oolite') 

 have been discovered at certain points of the South-Western 

 Province, and they are adumbrated at many others. [If, further- 

 more, we extend our researches and compare the Midland and 

 Northerii developments of England and Wales with that of Belgimn, 

 stiiking identities are observed ; for example : — 



The ' Brachiopod Beds ' of the Midlands and of Vis^ are identical. 

 The lower ' knolls ' of the Clitheroe area are typical ' Waulsortian.'] 



The following are the most impoi'tant conclusions from the 

 Author's work in Belgium : — 



I. Physiographical Phenomena. 

 The lateral variation of Mid-Avonian lithology is strikingly 

 exhibited in a diagram. Minute correlation of the Belgian 

 sequence with that of the South-Western Province demonstrates 

 that the periods of partial emergence — of the west of the South- 

 Westei'n Province and of the east of the Belgian Province — took 

 place consecutively and not simultaneously, namely : in the South- 

 Western Province at the close of C,-time, in Belgium at the 

 beginning of Visean time. At the latter period, England and 

 Wales, outside the South-Western Province, had sunk below the 

 Carboniferous sea. [Simultaneously, however, Ireland was, like 

 Belgium, under emergent conditions.] 



II. Palseontological Phenomena. 

 The pala^ontological section contains descriptions of several 

 gentes that are common in Belgium, but rare in Britain. The 

 most interesting portion of the section is, however, that which 

 deals with the evolution of the important Carboniferous corals 

 and V)rachiopods. Two illustrations were selected, and were shown 

 as lantern-slides : — 



(i) Phyloyonetic history of Caninin cylindrica. 

 ■r> , • 1 r K. Endophyllum. 



^' \ Z. Cnninia hastierensis (Endophylloid). 

 Migration into Britain at y — C. cylindrica, mut. y. 

 Britain and Bolg-ium ... { 5 and S- -mature (Campophylloid) Vaninin. 

 (ii) Fragments of the history of Spiriferina octoplicatd, showing vai-iation 

 of relative strength of ribs (departure from noruiulity of early stages) — 

 the essential characters fixed. 



These facts concerning migration and evolution are, un- 

 questionably, the UKjst im])ortant results of extending the area of 

 observation. 



